Telmisartan improves insulin resistance of skeletal muscle through peroxisome proliferator-activated receptor-δ activation

Effects of telmisartan on metabolic syndrome components: a comprehensive review

Telmisartan is an antagonist of the angiotensin II receptor used in the management of hypertension (alone or in combination with other antihypertensive agents. It belongs to the drug class of angiotensin II receptor blockers (ARBs). Among drugs of this class, telmisartan shows particular pharmacologic properties, including a longer half-life than any other angiotensin II receptor blockers that bring higher and persistent antihypertensive activity. In hypertensive patients, telmisartan has superior efficacy than other antihypertensive drugs (losartan, valsartan, ramipril, atenolol, and perindopril) in controlling blood pressure, especially towards the end of the dosing interval. Telmisartan has a partial PPARγ-agonistic effect whilst does not have the safety concerns of full agonists of PPARγ receptors (thiazolidinediones). Moreover, telmisartan has an agonist activity on PPARα and PPARδ receptors and modulates the adipokine levels. Thus, telmisartan could be considered as a suitable alternative option, with multi-benefit for all components of metabolic syndrome including hypertension, diabetes mellitus, obesity, and hyperlipidemia. This review will highlight the role of telmisartan in metabolic syndrome and the main mechanisms of action of telmisartan are discussed and summarized. Many studies have demonstrated the useful properties of telmisartan in the prevention and improving of metabolic syndrome and this well-tolerated drug can be greatly proposed in the treatment of different components of metabolic syndrome. However, larger and long-duration studies are needed to confirm these findings in long-term observational studies and prospective trials and to determine the optimum dose of telmisartan in metabolic syndrome.

Telmisartan versus metformin in downregulating myostatin gene expression and enhancing insulin sensitivity in the skeletal muscles of type 2 diabetic rat model

Objective: Telmisartan is an angiotensin receptor blocker (ARB) that specifically blocks angiotensin II type-1 receptors (AT1R). Telmisartan has been proven to have antidiabetic effects via a variety of mechanisms, and it can be utilized in some diabetic patients due to its dual benefit for hypertensive patients with type 2 DM (T2DM) and when the other oral antidiabetic medications are intolerable or contraindicated. However, its precise underlying hypoglycemic mechanism is still obscure. Aim of work: We sought to establish a link between telmisartan administration and myostatin expression in skeletal muscles of T2DM rat model as a potential hypoglycemic mechanism of telmisartan. Materials and Methods: 32 male albino rats were included in the study; 8 rats served as controls (group I). T2DM was inducted in the other 24 rats, which were then randomly subdivided into 3 groups (8 in each): (group II) the Diabetic group and (groups III and IV) which were treated with either telmisartan (8 mg/kg/day) or metformin (250 mg/kg/day) respectively via oral gavage for a 4-week period. Results: Telmisartan administration resulted in a significant improvement in OGTT, HOMA-IR, glucose uptake, and muscle mass/body ratios in Telmisartan group as compared to Diabetic group (p < 0.05). Additionally, telmisartan induced a significant boost in adiponectin and IL-10 serum levels with a substantial drop in TNF-α and IL-6 levels in Telmisartan group compared to diabetic rats (p < 0.05). Moreover, telmisartan significantly boosted SOD and GSH, and decreased MDA levels in the skeletal muscles of telmisartan group. Furthermore, a significant downregulation of myostatin and upregulation of insulin receptor, IRS-1, and IRS-3 genes in the skeletal muscles of Telmisartan group were also detected. Histologically, telmisartan attenuated the morphological damage in the skeletal muscle fibers compared to diabetic rats, as evidenced by a considerable decrease in the collagen deposition area percentage and a reduction in NF-kB expression in the muscle tissues of group III. Conclusion: Telmisartan administration dramatically reduced myostatin and NF-kB expressions in skeletal muscles, which improved insulin resistance and glucose uptake in these muscles, highlighting a novel antidiabetic mechanism of telmisartan in treating T2DM.

Pharmacological Utility of PPAR Modulation for Angiogenesis in Cardiovascular Disease

Peroxisome proliferator activated receptors, including PPARα, PPARβ/δ, and PPARγ, are ligand-activated transcription factors belonging to the nuclear receptor superfamily. They play important roles in glucose and lipid metabolism and are also supposed to reduce inflammation and atherosclerosis. All PPARs are involved in angiogenesis, a process critically involved in cardiovascular pathology. Synthetic specific agonists exist for all PPARs. PPARα agonists (fibrates) are used to treat dyslipidemia by decreasing triglyceride and increasing high-density lipoprotein (HDL) levels. PPARγ agonists (thiazolidinediones) are used to treat Type 2 diabetes mellitus by improving insulin sensitivity. PPARα/γ (dual) agonists are supposed to treat both pathological conditions at once. In contrast, PPARβ/δ agonists are not in clinical use. Although activators of PPARs were initially considered to have favorable effects on the risk factors for cardiovascular disease, their cardiovascular safety is controversial. Here, we discuss the implications of PPARs in vascular biology regarding cardiac pathology and focus on the outcomes of clinical studies evaluating their benefits in cardiovascular diseases.

Effect of Telmisartan on Walking Performance in Patients With Lower Extremity Peripheral Artery Disease: The TELEX Randomized Clinical Trial

Importance

Patients with lower extremity peripheral artery disease (PAD) have reduced lower extremity perfusion, impaired lower extremity skeletal muscle function, and poor walking performance. Telmisartan (an angiotensin receptor blocker) has properties that reverse these abnormalities.

Objective

To determine whether telmisartan improves 6-minute walk distance, compared with placebo, in patients with lower extremity PAD at 6-month follow-up.

Design, Setting, and Participants

Double-blind, randomized clinical trial conducted at 2 US sites and involving 114 participants. Enrollment occurred between December 28, 2015, and November 9, 2021. Final follow-up occurred on May 6, 2022.

Interventions

The trial randomized patients using a 2 × 2 factorial design to compare the effects of telmisartan plus supervised exercise vs telmisartan alone and supervised exercise alone and to compare telmisartan alone vs placebo. Participants with PAD were randomized to 1 of 4 groups: telmisartan plus exercise (n = 30), telmisartan plus attention control (n = 29), placebo plus exercise (n = 28), or placebo plus attention control (n = 27) for 6 months. The originally planned sample size was 240 participants. Due to slower than anticipated enrollment, the primary comparison was changed to the 2 combined telmisartan groups vs the 2 combined placebo groups and the target sample size was changed to 112 participants.

Main Outcomes and Measures

The primary outcome was the 6-month change in 6-minute walk distance (minimum clinically important difference, 8-20 m). The secondary outcomes were maximal treadmill walking distance; Walking Impairment Questionnaire scores for distance, speed, and stair climbing; and the 36-Item Short-Form Health Survey physical functioning score. The results were adjusted for study site, baseline 6-minute walk distance, randomization to exercise vs attention control, sex, and history of heart failure at baseline.

Results

Of the 114 randomized patients (mean age, 67.3 [SD, 9.9] years; 46 were women [40.4%]; and 81 were Black individuals [71.1%]), 105 (92%) completed 6-month follow-up. At 6-month follow-up, telmisartan did not significantly improve 6-minute walk distance (from a mean of 341.6 m to 343.0 m; within-group change: 1.32 m) compared with placebo (from a mean of 352.3 m to 364.8 m; within-group change: 12.5 m) and the adjusted between-group difference was -16.8 m (95% CI, -35.9 m to 2.2 m; P = .08). Compared with placebo, telmisartan did not significantly improve any of the 5 secondary outcomes. The most common serious adverse event was hospitalization for PAD (ie, lower extremity revascularization, amputation, or gangrene). Three participants (5.1%) in the telmisartan group and 2 participants (3.6%) in the placebo group were hospitalized for PAD.

Conclusions and Relevance

Among patients with PAD, telmisartan did not improve 6-minute walk distance at 6-month follow-up compared with placebo. These results do not support telmisartan for improving walking performance in patients with PAD.

Trial Registration

ClinicalTrials.gov Identifier: NCT02593110.

Comparative Study of the Effects of Azilsartan and Telmisartan on Insulin Resistance and Metabolic Biomarkers in Essential Hypertension Associated With Type 2 Diabetes Mellitus

Introduction

The complex interplay between the autonomic nervous system, renin-angiotensin-aldosterone system (RAAS), and immunity contributes to the pathogenesis of hypertension in diabetes mellitus. The objective of this study was to investigate and compare the effect of azilsartan and telmisartan on insulin resistance and metabolic biomarkers in patients with both hypertension and type 2 diabetes mellitus.

Methods

The present study was a prospective, randomized, active-controlled, open-label, parallel-group clinical trial. Patients with grade I or II essential hypertension with type 2 diabetes mellitus were randomized into two groups of 25 patients each. Baseline evaluation of homeostasis model assessment-insulin resistance (HOMA-IR), plasma glucose, insulin, leptin and adiponectin levels, and systolic and diastolic blood pressure (SBP and DBP) of patients was done. Patients were reassessed after 12 weeks of drug therapy with azilsartan 40 mg OD (once daily) or telmisartan 40 mg OD.

Results

The mean changes in HOMA-IR from the baseline at the end of 12 weeks of treatment were 0.15 (−0.64, 0.94.52) in the azilsartan group and 0.32 (−0.61, 1.26) in the telmisartan group. The mean difference in the changes from the baseline in HOMA-IR between the two groups was 0.3 (−0.87, 1.48), which was not statistically significant. No statistically significant changes were observed between the two groups in metabolic biomarkers (leptin: -0.84, CI: -4.83 to 3.14, and adiponectin: -0.12, CI: -0.62 to 0.37). Systolic (SBP) and diastolic blood pressure (DBP) decreased at the end of the 12-week treatment in both the groups; however, there was no significant difference between the two groups (SBP: -2.6, CI: -10.35 to 5.1, and DBP: -3.0, CI: -7.7 to 1.7).

Conclusion

Neither azilsartan nor telmisartan had any significant effects on insulin resistance and metabolic biomarkers after 12 weeks of drug therapy in hypertension patients associated with type 2 diabetes mellitus. However, they showed a comparable antihypertensive effect. The adverse effects observed were mild in nature, and their incidence was comparable between the two groups.

BCAA-BCKA axis regulates WAT browning through acetylation of PRDM16

The link between branched-chain amino acids (BCAAs) and obesity has been known for decades but the functional role of BCAA metabolism in white adipose tissue (WAT) of obese individuals remains vague. Here, we show that mice with adipose tissue knockout of Bcat2, which converts BCAAs to branched-chain keto acids (BCKAs), are resistant to high-fat diet-induced obesity due to increased inguinal WAT browning and thermogenesis. Mechanistically, acetyl-CoA derived from BCKA suppresses WAT browning by acetylation of PR domain-containing protein 16 (PRDM16) at K915, disrupting the interaction between PRDM16 and peroxisome proliferator-activated receptor-γ (PPARγ) to maintain WAT characteristics. Depletion of BCKA-derived acetyl-CoA robustly prompts WAT browning and energy expenditure. In contrast, BCKA supplementation re-establishes high-fat diet-induced obesity in Bcat2 knockout mice. Moreover, telmisartan, an anti-hypertension drug, significantly represses Bcat2 activity via direct binding, resulting in enhanced WAT browning and reduced adiposity. Strikingly, BCKA supplementation reverses the lean phenotype conferred by telmisartan. Thus, we uncover the critical role of the BCAA-BCKA axis in WAT browning.

Immunotherapy against angiotensin II receptor ameliorated insulin resistance in a leptin receptor-dependent manner

The angiotensin II type 1 receptor (AT1R) signaling pathway is reported to modulate glucose metabolism. Targeting AT1R, our group invented ATRQβ-001 vaccine, a novel immunotherapeutic strategy to block the activation of AT1R. Here, we evaluated the therapeutic efficacy of ATRQβ-001 vaccine in insulin resistance, and investigated the mechanism. Our results showed that ATRQβ-001 vaccine and specific monoclonal antibody against epitope ATR-001 (McAb-ATR) decreased fasting serum insulin concentration and improved glucose and insulin tolerance in ob/ob mice. These beneficial effects were verified in high-fat diet-induced obese mice. McAb-ATR activated insulin signaling in skeletal muscle and insulin-resistant C2C12 myotubes without affecting liver or white adipose tissue of ob/ob mice. Mechanistically, the favorable impact of McAb-ATR on insulin resistance was abolished in db/db mice and in C2C12 myotubes with leptin receptor knockdown. AT1R knockdown also eradicated the effects of McAb-ATR in C2C12 myotubes. Furthermore, McAb-ATR treatment was able to activate the leptin receptor-mediated JAK2/STAT3 signaling in skeletal muscle of ob/ob mice and C2C12 myotubes. Additionally, angiotensin II downregulated the leptin signaling in skeletal muscle of ob/ob and diet-induced obese mice. We demonstrated that ATRQβ-001 vaccine and McAb-ATR improved whole-body insulin resistance and regulated glucose metabolism in skeletal muscle in a leptin receptor-dependent manner. Our data suggest that immunotherapy targeting AT1R is a novel strategy for treating insulin resistance.

Telmisartan attenuates obesity-induced insulin resistance via suppression of AMPK mediated ER stress

Telmisartan is a known angiotensin II (Ang II) AT1 receptor blocker (ARB). While the beneficial effect of Telmisartan on glucose and lipid metabolism has been reported, the underlying molecular mechanism remained unclear. The endoplasmic reticulum (ER) stress is considered as one of important factors contributing to insulin resistance. In this study, we found that Telmisartan alleviated diet-induced obesity and insulin resistance, suppressed inflammation in adipose tissue, and alleviated hepatic steatosis. Furthermore, we showed that Telmisartan suppressed ER stress by activating AMP-activated protein kinase (AMPK) signaling pathway in vivo. In differentiated 3T3-L1 adipocytes, Telmisartan also improved palmitate acid (PA) induced ER stress. Compound C, an AMPK inhibitor, could abolish beneficial effect of Telmisartan on ER stress. Our data indicated Telmisartan improved obesity-induced insulin resistance through suppression of ER stress by activation of AMPK. These results provided the evidence that Telmisartan may have therapeutic potential for the treatment of obesity and type II diabetes.

Telmisartan increases hepatic glucose production via protein kinase C ζ-dependent insulin receptor substrate-1 phosphorylation in HepG2 cells and mouse liver

Background

Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.

Methods

Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.

Results

Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser³⁰²) and decreased p-IRS-1-Tyr⁶³² dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr⁴¹⁰ which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser³⁰² and -inhibited p-IRS-1-Tyr⁶³². Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser³⁰² and decreased p-IRS-1-Tyr⁶³², which was accompanied by an increase in p-PKCζ-Thr⁴¹⁰.

Conclusion

These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr⁴¹⁰ that increases p-IRS-1-Ser³⁰² and decreases p-IRS-1-Tyr⁶³² in a PPARγ-independent manner.

PPARδ: A Potential Therapeutic Target for the Treatment of Metabolic Hypertension

High blood pressure and its associated cardiovascular diseases have been major risks for public health. Multiple metabolic risk factors can cause the vascular dysfunction and vascular lesion, and the hypertension due to metabolic disturbances was defined as metabolic hypertension. The members of a subfamily of the nuclear receptors, peroxisome proliferator-activated receptors (PPARs), were found to be key regulators of metabolism and vascular function. We provide up-to-date knowledge on the role of subtype PPARδ in the regulation of metabolism and vascular function and the effect of its intervention on the metabolic hypertension management. We hope to give some insights into the development of more effective treatments of metabolic hypertension and its main complications.

Connectivity mapping of angiotensin-PPAR interactions involved in the amelioration of non-alcoholic steatohepatitis by Telmisartan

Nonalcoholic fatty liver disease (NAFLD) is a global health problem that is associated with various metabolic disorders. Telmisartan is a potential treatment for NAFLD due to its ability to improve insulin sensitivity and decrease hepatic fat accumulation via modulation of PPARγ, and to suppress hepatic fibrosis by blocking angiotensin II receptors. However, the underlying mechanisms of action of telmisartan have yet to be fully elucidated. In the present study, diabetic nonalcoholic steatohepatitis (NASH) mice (STAM mice) received daily administrations of telmisartan for 6 weeks to assess the improvements in NASH. Hepatic transcriptome analyses revealed that the amelioration of NASH likely occurred through the regulation of inflammatory- and fibrosis-related gene responses. An integrated network analysis including transcriptional and non-transcriptional genes regulated by telmisartan showed that the NAFLD pathway is interconnected with the dysregulated RAS-PPAR-NFκB pathways. The downstream targets of PPARα, PPARδ, and RELA in this network significantly overlapped with telmisartan-induced differentially expressed genes (DEGs), which were verified in palmitate-treated Hepa1c1c7 cell line. This transcriptome approach accompanied with cell-based molecular analyses provided the opportunity to understand the fundamental molecular mechanisms underpinning the therapeutic effects of telmisartan, and will contribute to the establishment of a novel pharmacological treatment for NASH patients.

The influence of telmisartan on metformin pharmacokinetics and pharmacodynamics

Metformin is the most widely used drug among type 2 diabetes mellitus patients. However, drug interaction on metformin will influence its glucose-lowering effect or increase its side effect of lactic acidosis. In this study, a randomized, two-stage, crossover study was conducted to unveil the potential drug interaction between metformin and the anti-hypertension drug, telmisartan. Totally, 16 healthy Chinese male volunteers were enrolled. Blood samples from various time-points after drug adminstration were analyzed for metformin quantification. Oral glucose tolerance test (OGTT) was conducted 2 h after metformin administration. The AUC_0-12 and Cmax of metformin in subjects co-administrated with telmisartan were significantly lower than with placebo. The geometric mean ratios (value of metformin plus telmisartan phase/value of metformin plus placebo phase) for Cmax and AUC_0-12 is 0.7972 (90%CI: 0.7202-0.8824) and 0.8336 (90%CI: 0.7696-0.9028), respectively. Moreover, telmisartan co-administration significantly increased the plasma concentrations of both glucose and insulin at 0.5 h since OGTT (7.64 ± 1.86 mmol/l·min vs 6.77 ± 0.83 mmol/l·min, P = 0.040; 72.91 ± 31.98 μIU/ml·min vs 60.20 ± 24.20 μIU/ml·min, P = 0.037), though the AUC of glucose and insulin after OGTT showed no significant difference. These findings suggested that telmisartan had a significant influence on the Pharmacokinetics of metformin in healthy groups, though the influence on glucose-lowering effect was moderate.

Sucrose nonfermenting AMPK-related kinase (SNARK) regulates exercise-stimulated and ischemia-stimulated glucose transport in the heart

The signaling mechanisms mediating myocardial glucose transport are not fully understood. Sucrose nonfermenting AMP-activated protein kinase (AMPK)-related kinase (SNARK) is an AMPK-related protein kinase that is expressed in the heart and has been implicated in contraction-stimulated glucose transport in mouse skeletal muscle. We first determined if SNARK is phosphorylated on Thr²⁰⁸ , a site critical for SNARK activity. Mice were treated with exercise, ischemia, submaximal insulin, or maximal insulin. Treadmill exercise slightly, but significantly increased SNARK Thr²⁰⁸ phosphorylation. Ischemia also increased SNARK Thr²⁰⁸ phosphorylation, but there was no effect of submaximal or maximal insulin. HL1 cardiomyocytes were used to overexpress wild-type (WT) SNARK and to knockdown endogenous SNARK. Overexpression of WT SNARK had no effect on ischemia-stimulated glucose transport; however, SNARK knockdown significantly decreased ischemia-stimulated glucose transport. SNARK overexpression or knockdown did not alter insulin-stimulated glucose transport or glycogen concentrations. To study SNARK function in vivo, SNARK heterozygous knockout mice (SNARK^+/- ) and WT littermates performed treadmill exercise. Exercise-stimulated glucose transport was decreased by ~50% in hearts from SNARK^+/- mice. In summary, exercise and ischemia increase SNARK Thr²⁰⁸ phosphorylation in the heart and SNARK regulates exercise-stimulated and ischemia-stimulated glucose transport. SNARK is a novel mediator of insulin-independent glucose transport in the heart.

Telmisartan is effective to ameliorate metabolic syndrome in rat model - a preclinical report

BACKGROUND

Metabolic syndrome (MS) is known to be associated with hypertension, insulin resistance, and dyslipidemia, and it raises the risk for cardiovascular diseases and diabetes mellitus. Telmisartan is used in clinic as an angiotensin II receptor blocker and it is also identified as activating peroxisome proliferator-activated receptors δ (PPARδ). Activation of PPARδ produced beneficial effects on fatty acid metabolism and glucose metabolism. This study aims to investigate the effects of telmisartan on the modulation of MS in rats fed a high-fat/high-sodium diet.

METHODS

Rats were fed with a high-fat/high-sodium diet and received injections of streptozotocin at low dose to induce MS. Then, rats with MS were treated with telmisartan. The weight, glucose tolerance, and insulin sensitivity were measured. The lipid profiles were also obtained. The weights of retroperitoneal and epididymal fat pads were determined. The role of PPARδ in telmisartan treatment was identified in rats pretreated with the specific antagonist GSK0660.

RESULTS

The results showed that telmisartan, but not losartan, significantly reduced plasma glucose and plasma insulin, and improved insulin resistance in rats with MS. Telmisartan also decreased blood pressure and lipids more significantly than losartan. Moreover, GSK0660 effectively reversed the effects of telmisartan in the MS rats. In the MS group, telmisartan activated PPARδ to enhance the levels of phosphorylated GLUT4 in muscle or the expression of phosphoenolpyruvate carboxykinase (PEPCK) in the liver, which was also abolished by GSK0660. Telmisartan is useful to ameliorate hypertension and insulin resistance in rats with MS. Telmisartan improves the insulin resistance through increased expression of GLUT4 and down-regulation of PEPCK via PPARδ-dependent mechanisms.

CONCLUSION

Telmisartan has been proven to ameliorate MS, particularly in the prediabetes state. Therefore, telmisartan is suitable to develop for the management of MS in clinics.

Controversy of oral hypoglycemic agents in type 2 diabetes mellitus: Novel move towards combination therapies

AIM

As diabetes mellitus is multi-factorial disease, use of several oral hypoglycemic agents (OHAs) is the main stay of pharmacological treatment. The treatment has become more challenging and controversial as OHAs are heterogeneous in their mode of action that causes unwanted side effects. Complementary approaches such as use of medicinal plants and dietary polyunsaturated fatty acids (PUFA) with hypoglycemic and hypolipidemic activities are therefore imperative. A vast literature has independently documented the effects of OHAs, medicinal plants and PUFA for management of diabetes. In the present article, we have reviewed the current literature to describe the effects of commonly used OHAs, their mechanisms of action and reported controversies. The antidiabetic potential of herbs and/or formulations and omega-3 PUFA with its potential benefits and mode of action is also discussed.

METHODS

PUBMED, MEDLINE, Cochrane Library etc., were searched for relevant articles using appropriate terms (until February 2015). Human and animal studies were selected for the review. Data extraction was carried out by one author and checked by second author.

RESULTS

There is still controversy over the safety profile of OHAs. Medicinal herbs with hypoglycemic activities are increasingly sought because of its natural origin, active constituents and minimal side effects. The current literature suggests that supplementation with PUFA improves macro- and microvascular complications.

CONCLUSION

There is a need for best possible individualized treatment based on variations in biochemical parameters with combinational therapy of nutritional/herbal supplementations. Such a combination may be helpful for better management of diabetes and its complications.

Telmisartan Activates PPARδ to Improve Symptoms of Unpredictable Chronic Mild Stress-Induced Depression in Mice

Major depression is a common mental disorder that has been established to be associated with a decrease in serotonin and/or serotonin transporters in the brain. Peroxisome proliferator-activated receptor δ (PPARδ) has been introduced as a potential target for depression treatment. Telmisartan was recently shown to activate PPARδ expression; therefore, the effectiveness of telmisartan in treating depression was investigated. In unpredictable chronic mild stress (UCMS) model, treatment with telmisartan for five weeks notably decrease in the time spent in the central and the reduced frequency of grooming and rearing in open filed test (OFT) and the decreased sucrose consumption in sucrose preference test (SPT) compared with the paradigms. Telmisartan also reversed the decrease in PPARδ and 5-HTT levels in the hippocampus of depression-like mice. Administration of PPARδ antagonist GSK0660 and direct infusion of sh-PPARδ into the brain blocked the effects of telmisartan on the improvement of depression-like behavior in these mice. Moreover, telmisartan enhanced the expression of PPARδ and 5HTT in H19-7 cells. In conclusion, the obtained results suggest that telmisartan improves symptoms of stress-induced depression in animals under chronic stress through activation of PPARδ. Therefore, telmisartan may be developed as a potential anti-depressant in the future.

Low expression of complement inhibitory protein CD59 contributes to humoral autoimmunity against astrocytes

Neuromyelitis optica spectrum disorder is primarily an anti-aquaporin 4 autoantibody-mediated, central nervous system-restricted channelopathy. Patients frequently develop central nervous system-restricted lesions even though autoantigen aquaporin 4 in neuromyelitis optica spectrum disorder is broadly distributed in the central nervous system and peripheral organs. The cause of such tissue-specific immune response remains largely unknown. We confirmed here that CD59, an inhibitory regulator of the complement membrane attack complex, is expressed and co-localized with aquaporin 4 in peripheral organs but is only minimally expressed in astrocytes in the central nervous system. In addition, we further found that CD59 overexpression in mouse brains decreased demyelination, blocked the loss of astrocytes and aquaporin 4, and inhibited membrane attack complex formation and infiltration of inflammatory cells. Inactivation of CD59 in mouse peripheral aquaporin 4-expressing cells and tissues led to complement-dependent cytotoxicity. In accordance with the mouse data, human samples presented higher expression of CD59 in many aquaporin 4-expressing peripheral tissues but not in astrocytes. Silencing or blocking CD59 in aquaporin 4-expressing human tracheal epithelial and skeletal muscle cells induced membrane attack complex formation and cytotoxicity, which suggests a protective role of CD59 in anti-aquaporin 4 antibodies-mediated complement toxicity. Our findings suggest that low CD59 expression in astrocytes may contribute to central nervous system-restricted lesions in neuromyelitis optica spectrum disorder. Restoring CD59 expression in astrocytes may serve as a novel therapeutic target of neuromyelitis optica spectrum disorder.

Enhanced Mitochondrial Transient Receptor Potential Channel, Canonical Type 3-Mediated Calcium Handling in the Vasculature From Hypertensive Rats

BACKGROUND

Mitochondrial Ca2+ homeostasis is fundamental to the regulation of mitochondrial reactive oxygen species (ROS) generation and adenosine triphosphate production. Recently, transient receptor potential channel, canonical type 3 (TRPC3), has been shown to localize to the mitochondria and to play a role in maintaining mitochondrial calcium homeostasis. Inhibition of TRPC3 attenuates vascular calcium influx in spontaneously hypertensive rats (SHRs). However, it remains elusive whether mitochondrial TRPC3 participates in hypertension by increasing mitochondrial calcium handling and ROS production.

METHODS AND RESULTS

In this study we demonstrated increased TRPC3 expression in purified mitochondria in the vasculature from SHRs, which facilitates enhanced mitochondrial calcium uptake and ROS generation compared with Wistar-Kyoto rats. Furthermore, inhibition of TRPC3 by its specific inhibitor, Pyr3, significantly decreased the vascular mitochondrial ROS production and H2O2 synthesis and increased adenosine triphosphate content. Administration of telmisartan can improve these abnormalities. This beneficial effect was associated with improvement of the mitochondrial respiratory function through recovering the activity of pyruvate dehydrogenase in the vasculature of SHRs. In vivo, chronic administration of telmisartan suppressed TRPC3-mediated excessive mitochondrial ROS generation and vasoconstriction in the vasculature of SHRs. More importantly, TRPC3 knockout mice exhibited significantly ameliorated hypertension through reduction of angiotensin II-induced mitochondrial ROS generation.

CONCLUSIONS

Together, we give experimental evidence for a potential mechanism by which enhanced TRPC3 activity at the cytoplasmic and mitochondrial levels contributes to redox signaling and calcium dysregulation in the vasculature from SHRs. Angiotensin II or telmisartan can regulate [Ca2+]mito, ROS production, and mitochondrial energy metabolism through targeting TRPC3.

Activation of TRPV4 by dietary apigenin antagonizes renal fibrosis in deoxycorticosterone acetate (DOCA)-salt-induced hypertension

Hypertension-induced renal fibrosis contributes to the progression of chronic kidney disease, and apigenin, an anti-hypertensive flavone that is abundant in celery, acts as an agonist of transient receptor potential vanilloid 4 (TRPV4). However, whether apigenin reduces hypertension-induced renal fibrosis, as well as the underlying mechanism, remains elusive. In the present study, the deoxycorticosterone acetate (DOCA)-salt hypertension model was established in male Sprague-Dawley rats that were treated with apigenin or vehicle for 4 weeks. Apigenin significantly attenuated the DOCA-salt-induced structural and functional damage to the kidney, which was accompanied by reduced expression of transforming growth factor-β1 (TGF-β1)/Smad2/3 signaling pathway and extracellular matrix proteins. Immunochemistry, cell-attached patch clamp and fluorescent Ca²⁺ imaging results indicated that TRPV4 was expressed and activated by apigenin in both the kidney and renal cells. Importantly, knockout of TRPV4 in mice abolished the beneficial effects of apigenin that were observed in the DOCA-salt hypertensive rats. Additionally, apigenin directly inhibited activation of the TGF-β1/Smad2/3 signaling pathway in different renal tissues through activation of TRPV4 regardless of the type of pro-fibrotic stimulus. Moreover, the TRPV4-mediated intracellular Ca²⁺ influx activated the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) pathway, which inhibited the TGF-β1/Smad2/3 signaling pathway. In summary, dietary apigenin has beneficial effects on hypertension-induced renal fibrosis through the TRPV4-mediated activation of AMPK/SIRT1 and inhibition of the TGF-β1/Smad2/3 signaling pathway. This work suggests that dietary apigenin may represent a promising lifestyle modification for the prevention of hypertension-induced renal damage in populations that consume a high-sodium diet.

Telmisartan improves cardiac fibrosis in diabetes through peroxisome proliferator activated receptor δ (PPARδ): from bedside to bench

BACKGROUND

Despite the known risk of diabetes-induced cardiac fibrosis, less is known about whether diabetes causes an altered cardiac phenotype independent of coronary atherosclerosis. Peroxisome proliferator-activated receptor δ (PPARδ), a versatile regulator of metabolic homeostasis, may be a potential therapeutic target. Herein we investigated the effectiveness of telmisartan, a unique angiotensin receptor blocker that increases PPARδ expression, in improving left ventricular remodeling in diabetic humans and rats.

METHODS

In this longitudinal, prospective study, we enrolled 15 diabetic patients receiving telmisartan (20 mg/day) for 12 weeks. After treatment, strain was measured and compared with the baseline value. Using streptozotocin to induce type 1 diabetes rat model, we measured PPARδ expression and downstream targets.

RESULTS

After treatment with telmisartan, both longitudinal and circumferential strains improved in diabetic patients. Compared with that of controls, the diabetic rat heart developed significant fibrosis, which markedly decreased after treatment with telmisartan (30 mg/kg/day, orally) for 7 days. After incubation with 30 mM glucose, rat cardiomyocytes showed a significant down-regulation of PPARδ. Interestingly, the increased expression of fibrosis-associated proteins, including signal transducer and activator of transcription 3 (STAT3) was attenuated by the co-incubation of GW0742, a PPARδ agonist. By knockdown or inhibition of STAT3, the hyperglycemia related high expression of fibrosis associated targets was reversed. Independent from the hyperglycemic incubation, STAT3 over-expression led to similar results. Conversely, in the presence of GSK0660, a PPARδ inhibitor, the protective effects of telmisartan were diminished.

CONCLUSION

Telmisartan improved the hyperglycemia-induced cardiac fibrosis through the PPARδ/STAT3 pathway. Graphical abstract Summary of the mechanism of telmisartan's effect on the suppression of hyperglycemia-induced cardiac fibrosis through PPARδ instead of the AMPK pathway. PPARδ peroxisome proliferator-activated receptor δ, STAT3 signal transducer and activator of transcription 3, CTGF connective tissue growth factor, MMP9 matrix metallopeptidase 9.

PPAR Ligands Function as Suppressors That Target Biological Actions of HMGB1

High mobility group box 1 (HMGB1), which has become one of the most intriguing molecules in inflammatory disorders and cancers and with which ligand-activated peroxisome proliferator-activated receptors (PPARs) are highly associated, is considered as a therapeutic target. Of particular interest is the fact that certain PPAR ligands have demonstrated their potent anti-inflammatory activities and potential anticancer effects. In this review article we summarize recent experimental evidence that PPAR ligands function as suppressors that target biological actions of HMGB1, including intracellular expression, receptor signaling cascades, and extracellular secretion of HMGB1 in cell lines and/or animal models. We also propose the possible mechanisms underlying PPAR involvement in inflammatory disorders and discuss the future therapeutic value of PPAR ligands targeting HMGB1 molecule for cancer prevention and treatment.

Effects of telmisartan on fat distribution: a meta-analysis of randomized controlled trials

OBJECTIVES

Several meta-analyses have confirmed the positive metabolic effects of telmisartan, an angiotensin II receptor blocker that can also act as a partial peroxisome proliferator-activated receptor-γ agonist, compared to those of other angiotensin II receptor blockers. These effects include decreased fasting glucose, glycosylated hemoglobin, interleukin-6, and tumor necrosis factor-α levels. However, no systemic analysis of telmisartan's effects on body fat distribution has been performed. We performed a meta-analysis of randomized controlled telmisartan trials to investigate its effects on body weight, fat distribution, and visceral adipose reduction.

RESEARCH DESIGN AND METHODS

A literature search was performed using Embase, MEDLINE, and the Cochrane Library between January 1966 and November 2013. Randomized controlled trials in English and meeting the following criterion were included: random assignment of hypertensive participants with overweight/obesity, metabolic syndrome, or glucose intolerance to telmisartan or control therapy group.

RESULTS

Of 651 potentially relevant reports, 15 satisfied the inclusion criterion. While visceral fat area was significantly lower in the telmisartan group than in the control group (weighted mean difference = -18.13 cm(2), 95% C.I. = -27.16 to -9.11, Pχ(2) = 0.19, I(2) = 41%), subcutaneous fat area was similar (weighted mean difference =2.94 cm(2), 95% C.I. = -13.01 to 18.89, Pχ(2) = 0.30, I(2) = 17%). Total cholesterol levels were significantly different between the groups (standardized mean difference = -0.24, 95% C.I. = -0.45 to -0.03, Pχ(2) = 0.0002, I(2) = 67%).

LIMITATIONS

Limitations include: (1) limited number of studies, especially those evaluating fat distribution; (2) different imaging modalities to assess visceral fat area (V.F.A.) and subcutaneous fat area (S.F.A.); (3) observed heterogeneity.

CONCLUSION

The findings suggest that telmisartan affected fat distribution, inducing visceral fat reduction, and thus could be useful in hypertensive patients with obesity/overweight, metabolic syndrome, or glucose intolerance.

Dexamethasone rapidly inhibits glucose uptake via non-genomic mechanisms in contracting myotubes

Glucocorticoids (GCs) are a class of steroid hormones that regulate multiple aspects of glucose homeostasis. In skeletal muscle, it is well established that prolonged GC excess inhibits glucose uptake and utilization through glucocorticoid receptor (GR)-mediated transcriptional changes. However, it remains obscure that whether the rapid non-genomic effects of GC on glucose uptake are involved in acute exercise stress. Therefore, we used electric pulse stimulation (EPS)-evoked contracting myotubes to determine whether the non-genomic actions of GC were involved and its underlying mechanism(s). Pretreatment with dexamethasone (Dex, 10 μM) significantly prevented contraction-stimulated glucose uptake and glucose transporter 4 (Glut4) translocation within 20 min in C2C12 myotubes. Neither GC nuclear receptor antagonist (RU486) nor protein synthesis inhibitor (cycloheximide, Chx) affected the rapid inhibition effects of Dex. AMPK and CaMKII-dependent signaling pathways were associated with the non-genomic effects of Dex. These results provide evidence that GC rapidly suppresses glucose uptake in contracting myotubes via GR-independent non-genomic mechanisms. AMPK and CaMKII-mediated Glut4 translocation may play a critical role in GC-induced rapid inhibition of glucose uptake.

Unraveling the Effects of PPARβ/δ on Insulin Resistance and Cardiovascular Disease

Insulin resistance precedes dyslipidemia and type 2 diabetes mellitus (T2DM) development. Preclinical evidence suggests that peroxisome proliferator-activated receptor (PPAR) β/δ activators may prevent and treat obesity-induced insulin resistance and T2DM, while clinical trials highlight their potential utility in dyslipidemia. This review summarizes recent mechanistic insights into the antidiabetic effects of PPARβ/δ activators, including their anti-inflammatory actions, their ability to inhibit endoplasmic reticulum (ER) stress and hepatic lipogenesis, and to improve atherogenesis and insulin sensitivity, as well as their capacity to activate pathways that are also stimulated by exercise. Findings from clinical trials are also examined. Dissecting the effects of PPARβ/δ ligands on insulin sensitivity and atherogenesis may provide a basis for the development of therapies for the prevention and treatment of T2DM and cardiovascular disease (CVD).

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Sodium Intake Regulates Glucose Homeostasis through the PPARδ/Adiponectin-Mediated SGLT2 Pathway

High sodium intake is a major risk factor for developing hypertension in diabetes. Promotion of sodium excretion reduces cardiometabolic lesions in diabetes. However, the interaction between sodium intake and glucose homeostasis remains elusive. Here, we report that high sodium intake remarkably increased natriuresis in wild-type mice, but this effect was blunted in adipose-specific PPARδ knockout mice and diabetic mice. PPARδ activation in perirenal fat by agonist or high sodium intake inhibited renal sodium-glucose cotransporter 2 (SGLT2) function, which is mediated by increased production of adipose adiponectin. In addition, high salt intake-induced natriuresis was impaired in diabetic states because of renal SGLT2 dysfunction. Type 2 diabetic patients with uncontrolled hyperglycemia had less natriuresis that was correlated to their plasma adiponectin levels. Our findings provide insights into the distinctive role of the PPARδ/adiponectin/SGLT2 pathway in the regulation of sodium and glucose homeostasis.

Night-time blood pressure: a role in the prediction and prevention of diabetes?

This commentary discusses and reviews the implications of two studies published in this issue of Diabetologia by Hermida et al (DOIs: 10.1007/s00125-015-3748-8 and 10.1007/s00125-015-3749-7 ) suggesting that high nocturnal blood pressure could have a role in the prediction of diabetes and act as a therapeutic target to prevent diabetes. This overview addresses the clinical implications of this work and new research that is likely to advance this field. It also provides a framework for interpreting claims of causality from observational studies and clinical trials.

Development of PPAR-agonist GW0742 as antidiabetic drug: study in animals

Background

The development of new drugs for the treatment of diabetes mellitus (DM) is critically important. Insulin resistance (IR) is one of the main problems associated with type-2 DM (T2DM) seen in clinics. GW0742, a selective peroxisome proliferator-activated receptor (PPAR)-δ agonist, has been shown to ameliorate metabolic abnormalities including IR in skeletal muscle in mice fed high-fructose corn syrup. However, the influence of GW0742 on systemic insulin sensitivity has still not been elucidated. Therefore, it is important to investigate the effect of GW0742 on systemic IR in diabetic rats for the development of new drugs.

Methods

The present study used a T2DM animal model to compare the effect of GW0742 on IR using homeostasis model assessment-IR (HOMA-IR) and hyperinsulinemic euglycemic clamping. Additionally, the insulinotropic action of GW0742 was investigated in type-1 DM (T1DM) rats. Changes in the protein expression of glucose transporter 4 (GLUT4) and phosphoenolpyruvate carboxykinase (PEPCK) in skeletal muscle and in liver, respectively, were also identified by Western blots.

Results

GW0742 attenuated the increased HOMA-IR in diabetic rats fed a fructose-rich diet. This action was blocked by GSK0660 at the dose sufficient to inhibit PPAR-δ. Improvement of IR by GW0742 was also characterized in diabetic rats using hyperinsulinemic euglycemic clamping. Additionally, an increase of insulin sensitivity due to GW0742 was observed in these diabetic rats. Moreover, GW0742 reduced the hyperglycemia in T1DM rats lacking insulin. Western blotting analysis indicated that GW0742 reversed the decrease in GLUT4 and markedly reduced the increased PEPCK in liver.

Conclusion

The data showed that GW0742 has the ability to improve glucose homeostasis in diabetic rats through activation of PPAR-δ. Therefore, PPAR-δ is a good target for the development of antidiabetic drugs in the future.

Prevalence of diabetic nephropathy in Type 2 Diabetes Mellitus in rural communities of Guanajuato, Mexico. Effect after 6 months of Telmisartan treatment

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Diabetic Nephropathy prevalence was determined in Mexican rural communities.

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We evaluated ARB treatment over 6 months in patients with Diabetic Nephropathy.

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We found a higher prevalence of DN than reported in Mexican National Health Survey.

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Subjects receiving ARB showed significant improvement in all parameters studied.

Objective

To determine the prevalence of Diabetic Nephropathy (DN) in patients with type 2 Diabetes Mellitus (T2DM) with over 5 years of evolution in rural communities of Guanajuato, Mexico, and evaluate the effects of an ARB treatment over 6 months in patients with DN.

Materials and methods

Patients of both sexes, 38–86 years, T2DM over 5 years of evolution and diagnosed with arterial hypertension (HT) after T2DM incidence. Monthly determination of microalbuminuria (MA), lipids, glucose, serum creatinine, and glycated hemoglobin (HbA1c). Estimated glomerular filtration rate (eGFR) by the Modification of Diet in Renal Disease (MDRD) formula. A dose of 80 mg of Telmisartan was administered daily over 6 months.

Results

The total adult population of two rural communities (3609 subjects) was studied, 335 subjects had T2DM, among them 80 (with a prevalence of 24%) had DN and HT. Sixty-seven patients received Telmisartan, and showed significant improvement in all parameters studied.

Conclusions

A higher prevalence of DN than that reported in the Mexican National Health Survey (ENSANUT) was found. Further research is required in a larger population sample in order to confirm the results of Telmisartan treatment.

Modulation of glucose metabolism by the renin-angiotensin-aldosterone system

The renin-angiotensin-aldosterone system (RAAS) is an enzymatic cascade functioning in a paracrine and autocrine fashion. In animals and humans, RAAS intrinsic to tissues modulates food intake, metabolic rate, adiposity, insulin sensitivity, and insulin secretion. A large array of observations shows that dysregulation of RAAS in the metabolic syndrome favors type 2 diabetes. Remarkably, angiotensin-converting enzyme inhibitors, suppressing the synthesis of angiotensin II (ANG II), and angiotensin receptor blockers, targeting the ANG II type 1 receptor, prevent diabetes in patients with hypertensive or ischemic cardiopathy. These drugs interrupt the negative feedback loop of ANG II on the RAAS cascade, which results in increased production of angiotensins. In addition, they change the tissue expression of RAAS components. Therefore, the concept of a dual axis of RAAS regarding glucose homeostasis has emerged. The RAAS deleterious axis increases the production of inflammatory cytokines and raises oxidative stress, exacerbating the insulin resistance and decreasing insulin secretion. The beneficial axis promotes adipogenesis, blocks the production of inflammatory cytokines, and lowers oxidative stress, thereby improving insulin sensitivity and secretion. Currently, drugs targeting RAAS are not given for the purpose of preventing diabetes in humans. However, we anticipate that in the near future the discovery of novel means to modulate the RAAS beneficial axis will result in a decisive therapeutic breakthrough.

Neuroprotective effects of angiotensin receptor blockers

Angiotensin II receptor blockers (ARBs, collectively called sartans) are widely used compounds therapeutically effective in cardiovascular disorders, renal disease, the metabolic syndrome, and diabetes. It has been more recently recognized that ARBs are neuroprotective and have potential therapeutic use in many brain disorders. ARBs ameliorate inflammatory and apoptotic responses to glutamate, interleukin 1β and bacterial endotoxin in cultured neurons, astrocytes, microglial, and endothelial cerebrovascular cells. When administered systemically, ARBs enter the brain, protecting cerebral blood flow, maintaining blood brain barrier function and decreasing cerebral hemorrhage, excessive brain inflammation and neuronal injury in animal models of stroke, traumatic brain injury, Alzheimer's and Parkinson's disease and other brain conditions. Epidemiological analyses reported that ARBs reduced the progression of Alzheimer's disease, and clinical studies suggested amelioration of cognitive loss following stroke and aging. ARBs are pharmacologically heterogeneous; their effects are not only the result of Ang II type 1(AT1) receptor blockade but also of additional mechanisms selective for only some compounds of the class. These include peroxisome proliferator-activated receptor gamma activation and other still poorly defined mechanisms. However, the complete pharmacological spectrum and therapeutic efficacy of individual ARBs have never been systematically compared, and the neuroprotective efficacy of these compounds has not been rigorously determined in controlled clinical studies. The accumulation of pre-clinical evidence should promote further epidemiological and controlled clinical studies. Repurposing ARBs for the treatment of brain disorders, currently without effective therapy, may be of immediate and major translational value.

Telmisartan attenuates myocardial apoptosis induced by chronic intermittent hypoxia in rats: modulation of nitric oxide metabolism and inflammatory mediators

PURPOSE

NO and NO synthase (NOS) are known to play key roles in the development of myocardial apoptosis induced by ischemia/hypoxia. Current evidence suggests that angiotensin II type 1 receptor blockers, such as telmisartan, lower blood pressure and produce beneficial regulatory effects on NO and NOS. Here, we examined the protective role of telmisartan in myocardial apoptosis induced by chronic intermittent hypoxia (CIH).

METHODS

Adult male Sprague-Dawley rats were subjected to 8 h of intermittent hypoxia/day, with/without telmisartan for 8 weeks. Myocardial apoptosis, NO and NOS activity, and levels of inflammatory mediators and radical oxygen species were determined.

RESULTS

Treatment with telmisartan preserved endothelial NOS expression and inhibited inducible NOS and excessive NO generation, while reducing oxidation/nitration stress and inflammatory responses. Administration of telmisartan before CIH significantly ameliorated the CIH-induced myocardial apoptosis.

CONCLUSIONS

This study show that pre-CIH telmisartan administration ameliorated myocardial injury following CIH by attenuating CIH-induced myocardial apoptosis via regulation of NOS activity and inhibition of excessive NO generation, oxidation/nitration stress, and inflammatory responses.

Enhanced pan-peroxisome proliferator-activated receptor gene and protein expression in adipose tissue of diet-induced obese mice treated with telmisartan

Telmisartan has previously been used to target obesity, showing peroxisome proliferator-activated receptor (PPAR) β/δ-related effects in white adipose tissue (WAT). We sought to evaluate whether telmisartan enhances gene and protein expression of all PPAR isoforms in WAT and brown adipose tissue (BAT), as well as their downstream effects upon insulin resistance, adipokine profile and adaptive thermogenesis. Male C57BL/6 mice were fed standard chow (SC; 10% lipids) or high-fat diet (HF; 50% lipids) for 10 weeks. Animals were then randomly allocated into the following four groups: SC, SC-T, HF and HF-T. Telmisartan [10 mg (kg diet)(-1)] was administered for 4 weeks in the diet. Animals in the HF group were overweight and exhibited hypertension, insulin resistance, decreased energy expenditure, a pro-inflammatory adipokine profile and abnormal fat pad mass distribution. Animals in the HF group showed decreased expression of PPARα, β/δ and γ in WAT and BAT, resulting in impaired glucose uptake and insufficient thermogenesis. Due to the improvement in the adipokine profile and enhanced insulin sensitivity with adequate insulin-stimulated glucose uptake after treatment with telmisartan, the activation of all PPAR isoforms in WAT was beneficial. In BAT, telmisartan induced sustained sympathetic activation, because the β3-adrenergic receptor was induced by PPARβ/δ, while uncoupling protein 1 was induced by PPARα to promote thermogenesis. Telmisartan exerted anti-obesity effects through higher pan-PPAR gene and protein expression. Upon PPARα, β/δ and γ (pan-PPAR) agonism in adipose tissue of obese mice, telmisartan ameliorates inflammation and insulin resistance, as well as inducing non-shivering thermogenesis. Our results point to new therapeutic targets for the control of obesity and comorbidities through pan-PPAR-related effects.

Involvement of proteasome and macrophages M2 in the protection afforded by telmisartan against the acute myocardial infarction in Zucker diabetic fatty rats with metabolic syndrome

This study investigated the involvement of proteasome and macrophages M2 in the protection afforded by telmisartan against the acute myocardial infarction in Zucker diabetic fatty (ZDF) rats with metabolic syndrome. ZDF rats were treated for three weeks with telmisartan at doses of 7 and 12 mg/kg/day. After treatment, rats were subjected to a 25 min occlusion of the left descending coronary artery followed by 2 h reperfusion (I/R). At the end of the I/R period, biochemical, immunohistochemical, and echocardiographic evaluations were done. Telmisartan treatment (7 mg/kg and 12 mg/kg) reduced the myocardial infarct size, the expression of proteasome subunits 20S and 26S, and the protein ubiquitin within the heart. The compound has led to an increased M2 macrophage phenotype within the cardiac specimens and a modification of the cardiac cytokine and chemokine profile. This was functionally translated in improved cardiac performance as evidenced by echography after 2 h reperfusion. 7 mg/kg/day telmisartan was sufficient to improve the left ventricular ejection fraction LVEF of the rat heart recorded after I/R (e.g., vehicle 38 ± 2.2%; telmisartan 54 ± 2.7%) and was sufficient to improve the diastolic function and the myocardial performance index up to values of 0.6 ± 0.01 measured after I/R.

High sugar intake and development of skeletal muscle insulin resistance and inflammation in mice: a protective role for PPAR- δ agonism

Peroxisome Proliferator Activated Receptor (PPAR)-δ agonists may serve for treating metabolic diseases. However, the effects of PPAR-δ agonism within the skeletal muscle, which plays a key role in whole-body glucose metabolism, remain unclear. This study aimed to investigate the signaling pathways activated in the gastrocnemius muscle by chronic administration of the selective PPAR-δ agonist, GW0742 (1 mg/kg/day for 16 weeks), in male C57Bl6/J mice treated for 30 weeks with high-fructose corn syrup (HFCS), the major sweetener in foods and soft-drinks (15% wt/vol in drinking water). Mice fed with the HFCS diet exhibited hyperlipidemia, hyperinsulinemia, hyperleptinemia, and hypoadiponectinemia. In the gastrocnemius muscle, HFCS impaired insulin and AMP-activated protein kinase signaling pathways and reduced GLUT-4 and GLUT-5 expression and membrane translocation. GW0742 administration induced PPAR-δ upregulation and improvement in glucose and lipid metabolism. Diet-induced activation of nuclear factor-κB and expression of inducible-nitric-oxide-synthase and intercellular-adhesion-molecule-1 were attenuated by drug treatment. These effects were accompanied by reduction in the serum concentration of interleukin-6 and increase in muscular expression of fibroblast growth factor-21. Overall, here we show that PPAR-δ activation protects the skeletal muscle against the metabolic abnormalities caused by chronic HFCS exposure by affecting multiple levels of the insulin and inflammatory cascades.